In my job I see a lot of old ladies taking money out of their breasts. It's like their pockets. These days the bills are fcking sweaty bruh. So they do get that big, but won't stay perky for long. Gravity is their no. 1 sworn enemy. They also giggle a lot even tho they just moved a bit. Quick glances are fine, just don't stare like the FMC to MC (don't ask me how I know).
Not necessarily big breasts = tumours/lumps. It's genetics. Some tumours could be benign.
If you ever have a gf and you notice a lump that was not there before, get that checked. As a good bf you are supposed to know the nooks and crannies of thy partner.